drm/msm/dp: add module parameter for PSR

drm/msm/dp: add module parameter for PSR

On sc7280 where eDP is the primary display, PSR is causing
IGT breakage even for basic test cases like kms_atomic and
kms_atomic_transition. Most often the issue starts with below
stack so providing that as reference

Call trace:
 dpu_encoder_assign_crtc+0x64/0x6c
 dpu_crtc_enable+0x188/0x204
 drm_atomic_helper_commit_modeset_enables+0xc0/0x274
 msm_atomic_commit_tail+0x1a8/0x68c
 commit_tail+0xb0/0x160
 drm_atomic_helper_commit+0x11c/0x124
 drm_atomic_commit+0xb0/0xdc
 drm_atomic_connector_commit_dpms+0xf4/0x110
 drm_mode_obj_set_property_ioctl+0x16c/0x3b0
 drm_connector_property_set_ioctl+0x4c/0x74
 drm_ioctl_kernel+0xec/0x15c
 drm_ioctl+0x264/0x408
 __arm64_sys_ioctl+0x9c/0xd4
 invoke_syscall+0x4c/0x110
 el0_svc_common+0x94/0xfc
 do_el0_svc+0x3c/0xb0
 el0_svc+0x2c/0x7c
 el0t_64_sync_handler+0x48/0x114
 el0t_64_sync+0x190/0x194
---[ end trace 0000000000000000 ]---
[drm-dp] dp_ctrl_push_idle: PUSH_IDLE pattern timedout

Other basic use-cases still seem to work fine hence add a
a module parameter to allow toggling psr enable/disable till
PSR related issues are hashed out with IGT.

Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Rob Clark <robdclark@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/534420/
Link: https://lore.kernel.org/r/20230427232848.5200-1-quic_abhinavk@quicinc.com
Signed-off-by: Rob Clark <robdclark@chromium.org>